Removing anti-freeze

E

engguy

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Jul 10, 2004
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14297
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After flushing my Alpha One with anti-freeze do I leave the anti-freeze in the engine or drain any of it? - I've had mixed opinions on this

I live in Vermont, and my boat sits on my trailer for the winter. I flush by running anti-freeze through the system via the sea-water inlet from a 5 gallon bucket ( ant then fogging).
 
What were the reasons against just leaving the anti freeze in ?
 
Never got a reason, I suspect it's because then there's nothing to freeze if the temp drops bellow the rating. But I'm not sure I'm sold on that ( and I'll use the -100) which is why unless I hear a better one I'm planning on leaving the stuff in. I'll make sure the engine is warm and the thermostat opens before sucking in the anti-freeze.
 
If this is a raw water cooled engine, that's not really the best way to do it because if the thermostat does not open all the way, you can get full strength antifreeze in the manifolds and a weak antifreeze + water mix in the block, which could freeze. I tried this once, check the block drains, what drained out was mostly water, with a bit of AF in it...
If you want to leave it in, which does help with reducing corrosion, the best way is to flush the engine, fog it, drain everything manually, poke the holes to make sure, and then replace the drain plugs and back fill the engines and manifolds with -100 with has more than enough freeze protection, even if a bit of water did not drain....I've done it this way for years and never had a problem...
The other way, has resulted in popped core plugs and cracked blocks in the spring. It is possible on a cold fall day that the thermostat would take a long time to open, on a raw water cooled engine with cold water from the hose running through it..
If you don't want to use AF then just drain it, poke the holes....
 
That's good advice Lou. Everytime I tried to run cold antifreeze thru a hot engine, I got a very dilute mixture in the blocks. Pays to test the blocks after. those that don't are sleeping well now but might have nightmares in the spring.
 
I find it easier, less stressful, to just drain it like you are supposed to and then if you want to use AF for corrosion protection, then back fill with AF. You may or may not get the thermostat to open when the engine is running on the muffs, on a cool fall day. Too much of a gamble. I think this way you can fog it without worrying about the AF running out, you use less AF and most importantly you know for sure your engine is full of AF of adequate freeze protection. I would only use the suck the AF up the drive method on an engine with closed cooling, to winterize the raw water side. Not for raw water cooled inboards....
 
I had raw water cooled motors until a few weeks ago. The new ones have half system FWC kits on them.
What I did with my raw water cooled motors was to drain the blocks making sure to poke in the drain holes with a nail to get a good flow, then I closed the drain plugs, pulled the big hose off of the T-Stat housing and poured AF down that hose until it came out through the T-Stat housing. It was real simple.
With the newly installed motors I winterized the raw water side of the heat exchanger, hoses and manifolds with the drives off by first draining everything and then pumping AF manually in through the intake back on the gimble assembly.
I found that a 3/4" ID 1" OD heater hose jammed in there nicely. I just had to buy some fittings and clear tubing in Lowe's to put it all together and make it work.
I pumped until I saw the AF coming out of the exhaust full strength an each engine and I was done.
 
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